Upper Bound Analysis for Collapse Failure of Shield Tunnel Face Excavated in Unsaturated Soils Considering Steady Vertical Flow

Table 3

Comparison of the collapse pressure with analytical results.

Friction angle ()	This study	Mollon et al. [17]	Xu et al. [33]
30	38.02	38.85	37.51
35	28.49	29.09	28.04
40	21.47	21.98	21.09
45	16.12	16.56	15.80